Allocation of Attentional Resources toward a Secondary Cognitive Task Leads to Compromised Ankle Proprioceptive Performance in Healthy Young Adults

The objective of the present study was to determine whether increased attentional demands influence the assessment of ankle joint proprioceptive ability in young adults. We used a dual-task condition, in which participants performed an ankle ipsilateral position-matching task with and without a secondary serial auditory subtraction task during target angle encoding. Two experiments were performed with two different cohorts: one in which the auditory subtraction task was easy (experiment 1a) and one in which it was difficult (experiment 1b). The results showed that, compared with the single-task condition, participants had higher absolute error under dual-task conditions in experiment 1b. The reduction in position-matching accuracy with an attentionally demanding cognitive task suggests that allocation of attentional resources toward a difficult second task can lead to compromised ankle proprioceptive performance. Therefore, these findings indicate that the difficulty level of the cognitive task might be the possible critical factor that decreased accuracy of position-matching task. We conclude that increased attentional demand with difficult cognitive task does influence the assessment of ankle joint proprioceptive ability in young adults when measured using an ankle ipsilateral position-matching task. 1. Introduction Ankle proprioception is critical to maintaining balance during functional activities such as standing and walking [1, 2]. Although there is general consensus on the role of visual, vestibular, and proprioceptive senses in the maintenance of upright posture [3, 4], studies have indicated that the somatosensory system is an important contributor to the feedback for postural control [5]. Previous studies have also suggested that decreased in proprioception in the lower limbs contributes significantly to instability and falls [5, 6]. In rehabilitation, proprioception should be evaluated because of its significance in motor control. Although several methods are available, the joint position-matching task is one of the most reliable tools for the assessment of proprioceptive acuity in the clinic and the laboratory [7–10]. In this test, a participant is asked to reposition a reference joint angle without observing the positioning and repositioning of the joint. Specifically, in ipsilateral position-matching tasks, where the same limb is used for reference and position matching, it is necessary to use memory in order to remember the target position [7]. Hence it is likely that some portion of any position-matching error reflects cognitive